Fastener assembly

ABSTRACT

A fastener assembly includes a threaded bolt and a locking nut assembly. The threaded bolt includes at least one longitudinal groove. The locking nut assembly includes a nut adapted to threadingly engage the bolt, a locking ring adapted to engage the bolt and the nut, and a biasing member adapted to bias the locking ring. The nut includes a threaded bore dimensioned to receive the bolt and a plurality of teeth formed on a face of the nut. The locking ring includes at least one inwardly protruding tab dimensioned to be received by the at least one longitudinal groove of the threaded bolt and a plurality of teeth formed on a face of the ring. The teeth on the face of the locking ring cooperate with the teeth on the face of the nut to inhibit removal of the nut from the bolt after the nut has been tightened. A method for manufacturing the fastener assembly and a tool for use with the fastener assembly is also provided.

This application claims the priority benefit of U.S. patent applicationSer. No. 11/838,640 filed Aug. 14, 2007, which claims the prioritybenefit of U.S. patent application Ser. No. 11/084,926, filed Mar. 21,2005; which claims the priority benefit of U.S. Provisional PatentApplication Ser. No. 60/555,249, filed Mar. 22, 2004 and U.S.Provisional Patent Application Ser. No. 60/568,963, filed May 7, 2004,each of which is incorporated by reference herein in its entirety.

BACKGROUND

A need exists for threaded fasteners that can withstand vibrationcycling with minimum loss of clamping force, i.e., axial load. It isalso desirable to provide a fastener having a removal torque thatmatches or exceeds an installation torque. Such a fastener reduces theeffects of tampering.

Known self-locking fasteners that inhibit removal of a tightened nutfrom a threaded bolt allow the bolt to be rotated as much as 40 degreesbefore the nut engages so that it no longer rotates. It has been foundthat a ⅜″ diameter bolt with 16 threads per inch that secures two ½″plates, so that the length of the bolt under a clamp load is 1″, losestwo-thirds of its load on the plates when rotated about 12 degrees in anuntightening direction. With the known self-locking fasteners, the boltand nut may still be retaining the plates after the nut has been rotated40 degrees in the untightening direction; however, the bolt has lost itsload and no longer retains the plates tightly.

Other self-locking fastener assemblies use teeth that engage one anotherto limit rotational movement of the nut with respect to the bolt. Thebolt engages a locking ring that has a plurality of teeth formed on aface that is normal to the longitudinal axis of the bolt. A nut that isthreaded onto the bolt also includes a face having a plurality of teeththat engage the teeth of the locking ring. In known assemblies, however,the teeth in the locking ring and the teeth on the bolt are disposed ata positive rake angle in the untightening direction and in thetightening direction. That is, the apex of each tooth follows the pointwhere the base joins the face for each tooth in both the tightening andthe untightening rotational direction.

SUMMARY

A fastener assembly includes a threaded bolt and a locking nut assembly.The threaded bolt includes at least one longitudinal groove. The lockingnut assembly includes a nut adapted to threadingly engage the bolt, alocking ring adapted to engage the bolt and the nut, and a biasingmember adapted to bias the locking ring. The nut includes a threadedbore dimensioned to receive the bolt and a plurality of teeth formed ona face of the nut. The locking ring includes at least one inwardlyprotruding tab dimensioned to be received by the at least onelongitudinal groove of the threaded bolt and a plurality of teeth formedon a face of the ring. The teeth on the face of the locking ringcooperate with the teeth on the face of the nut to inhibit removal ofthe nut from the bolt after the nut has been tightened.

A method for manufacturing a locking nut assembly includes the followingsteps: providing powdered metal into a nut mold; forming a nut;sintering the nut; providing powdered metal into a locking ring mold;forming a locking ring; and sintering the locking ring. The nut and thelocking ring manufactured using this method can be similar to thosedescribed above.

A fastener assembly can also include a bolt, a biasing member, a firstring, and a locking ring. The bolt can be similar to the bolt describedabove. The biasing member can be similar to the biasing member describedabove. The first ring is also adapted to receive the bolt and has aperipheral edge that is not symmetrical about a rotational axis of thebolt. The first ring is received between the head of the bolt and thebiasing member. The first ring includes at least two teeth formed on aface. The locking ring can be similar to the locking ring describedabove. The locking ring and the first ring cooperate with one another ina manner similar to the nut and the locking ring, which is describedabove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a bolt for use with a locking nutassembly.

FIG. 2 is a perspective view of the locking nut assembly for use withthe bolt of FIG. 1.

FIG. 3 is an exploded perspective view of the locking nut assembly ofFIG. 2.

FIG. 4 is an exploded perspective view, opposite the view of FIG. 3, ofthe locking nut assembly of FIG. 2.

FIG. 5 is a close-up view of teeth of the locking ring riding over teethof the nut as the locking ring is rotated in relation to the nut, orvice versa.

FIG. 6 is a close-up view of the teeth of a locking ring engaging theteeth of a nut of the locking nut assembly.

FIG. 7 is an exploded perspective view of an alternative embodiment of afastener assembly for use with a blind hole.

FIG. 8 is a perspective view, opposite the view depicted in FIG. 7, of aportion of the fastener assembly depicted in FIG. 7.

FIG. 9 is a perspective view of a removal tool for removing the lockingnut assembly of FIG. 2 from the bolt shown in FIG. 1.

FIG. 10 is a perspective view of the removal tool cooperating with a nutof the locking nut assembly shown in FIG. 2.

FIG. 11 is an exploded perspective view of the removal tool of FIG. 9.

FIG. 12 is a perspective view of the nut of the locking nut assemblyshown in FIG. 2 and an alternative embodiment of a removal tool.

FIG. 13 is a perspective view of the removal tool of FIG. 11 with anouter housing thereof removed to show the internal components of theremoval tool.

FIG. 14 is a side cross-sectional view of the removal tool depicted inFIG. 12.

FIG. 15 is a perspective view of a cover for use with the nut of thelocking nut assembly shown in FIG. 2.

DETAILED DESCRIPTION

With reference to FIGS. 1 and 2, a self-locking fastener assemblyincludes a bolt 10 (FIG. 1) and nut locking assembly 12 (FIG. 2). Thebolt 10 includes a shank 14 having threads 16. The shank 14 extends froma bolt head 18. Longitudinal grooves 22 that run parallel to alongitudinal axis of the bolt 10 are roll formed or cut just below theminor diameter of the threads 16. Even though it is not shown, thethreads 16 and the longitudinal grooves 22 can run the entire length ofthe shank 14. The fastener 10 can be made from conventional materialssuch as hardened steel, titanium and the like.

The nut locking assembly 12 shown in FIG. 2 is received on the bolt 10.The nut locking assembly 12 includes a nut 24, an interlocking ring 26,and a biasing member 28. With reference to FIG. 3, the nut 24 includes athreaded bore 32 that is configured to received the threaded portion ofthe bolt 10. The nut 24 also includes a counterbore 34 that is coaxialwith the threaded bore 32 and is dimensioned to receive the interlockingring 26 and the biasing member 28, as seen in FIG. 2. The counterborehas a depth equal to or slightly less than the thickness of theinterlocking ring 26 and the biasing member 28 so that the biasingmember extends from the counterbore. A plurality of teeth 36 are formedon a recessed base 38 at the bottom of the counterbore 34. The recessedface 38 is substantially normal to a longitudinal axis of the nut 24 andthe teeth 36 extend upwardly from the recessed face in a directiongenerally aligned with the longitudinal axis. The teeth 36 are formedhaving a negative rake, which will be described in more detail below.

The interlocking ring 26 includes a central opening 42 that isdimensioned to receive the bolt 10 (FIG. 1). Even though theinterlocking ring takes the form of a continuous circular band, theinterlocking ring can have other configurations that are not continuous.The interlocking ring includes a plurality of inwardly extending tabs 44that are dimensioned to be received by the longitudinal grooves 22 ofthe bolt 10 (FIG. 1). The tabs 44 engage the longitudinal grooves 22 sothat rotation of the bolts 10 results in rotation of the interlockingring 26. As more clearly seen in FIG. 4, the interlocking ring 26includes a plurality of teeth 46 formed on a face 48 of the interlockingring. The teeth 46 of the interlocking ring 26 selectively engage theteeth 36 of the nut 24, which will be described in more detail below.

The biasing member 28 includes outwardly extending fingers 52 thatextend radially from a peripheral edge 54 of the biasing member 28. Inthe embodiment depicted, the biasing member 28 is made of an elastomericmaterial, such as Viton, FEP, or Santoprene®. The biasing member 28 canbe dimensioned to snugly fit inside the counterbore 34 (FIG. 3) of thenut 24. The counterbore 34 can limit the tendency for the biasing member28 to flatten out as an axially load is applied to the biasing member.As more clearly seen in FIG. 3, the nut 24 includes an annular shoulder56 having a plurality of recesses 58 extending radially into theshoulder. Since the counterbore 34 will typically be manufactured with adraft angle, the recesses 58 are shaped to receive the fingers 52 of thebiasing member 28 to retain the interlocking ring 26 inside thecounterbore 34. The fingers 52 can also define openings 62 between theperipheral edge 54 of the biasing member 28 and the finger 52. Theopenings 62 allow the fingers 52 to deflect inwardly, i.e. toward theradial centerline of each opening 62, so that when pressed into therecesses 58 the fingers can exert an outward force to retain theinterlocking ring 26 inside the counterbore 34. Also, glue or otheradhesive can be dispensed into the openings 62 to further retain thebiasing member 28 in the counterbore 34.

The self-locking characteristics of the fastener assembly will bedescribed in more detail. The nut locking assembly 12 is threaded ontothe bolt 10 with the item to be fastened interposed between the shoulder56 of the nut 24 and the head 18 of the bolt 10 (FIG. 1). With referenceto FIG. 5, a close-up view of the cooperation between the teeth isshown. FIG. 5 represents movement of the locking ring 26 in relation tothe nut 24 as the bolt 10 is tightened. As the bolt 10 is tightened, asdepicted by arrow A in FIG. 5, the tabs 44 of the interlocking ring 26engage the longitudinal grooves 22 of the bolt 10 so that theinterlocking ring rotates in the direction of the arrow in FIG. 5. Asthe nut 24 is tightened, the nut 24 moves in the direction as depictedby arrow B.

Each tooth 36 and 46 has a negative rake in the untightening direction,which is explained below, to form a negative rake angle α, which can bebetween 0°-90°, and preferably between 1°-10°. Even though the teeth 36and 46 are depicted as having the same configurations and dimensions,the teeth 36 on the nut 24 can be shaped differently than the teeth 46on the interlocking ring 26 and can even have a different rake angle.Providing teeth having different configurations, e.g. different rakeangles, can provide relief for any debris that may gather around theteeth that might inhibit the teeth from engaging one another. As thebolt 10 is tightened, the interlocking ring 26 is rotated in atightening rotational direction (arrow A). An apex 64, which is theoutermost point of the tooth 46, follows behind a corresponding root 66,which is a point where a trailing edge 68 of the tooth intersects theface 44 of the interlocking ring 26. Likewise, as the nut 24 istightened an apex 72 of each tooth 36 on the nut 24 follows a root 74 ofthe corresponding tooth 36 of a trailing edge 76 (arrow B). Each tooth46 of the interlocking ring 26 also includes an inclined leading surface78 and likewise each tooth 36 of the nut 24 also includes an inclineleading surface 82. The biasing member 28 allows the interlocking ring26 to rotate freely in the tightening direction without displacingmaterial in the ring 26 or the nut 24. The interlocking ring 26 willmove axially along the bolt 10 as the inclined leading surface 78 ofeach tooth 46 of the interlocking ring rides along the inclined surface82 of each tooth 36 of the nut 24. After each tooth rides over acorresponding tooth, the biasing member 28 provides a constant seatingpressure on the interlocking ring 26.

With reference to FIG. 6, because of the negative rake formed in theteeth 36 and 46, rotational movement in the untightening direction, asshown by arrows C and D in FIG. 6, results in the teeth 36 and 46actively engaging one another to prohibit or substantially inhibitrotation in the untightening direction. In an attempt to untighten thebolt 10 or nut 24 the apex 64 of each tooth 46 of the interlocking ring26 precedes the root 66 of the trailing edge 68. Likewise, the apex 72of the trailing edge 76 precedes the root 74. Accordingly, the apex 64of each tooth 46 of the interlocking ring 26 is encouraged to moveaxially towards the root 74 of each tooth 36 of the nut 24 as the boltis rotated in an untightening rotational direction.

The forces on the trailing edge of each tooth encourage further seatingof the interlocking ring and the nut. Since the teeth are formed havinga negative rake, the vector component of the force on the trailing edgethat is parallel to the trailing edge points downward toward the root ofthe tooth because the sine of a negative angle is negative.

The removal torque of the fastener assembly can be tuned throughmultiple methods. A first tuning method removes some of the teeth oneither the locking ring or the nut. The second method is by adjustingthe total shear area of the teeth.

Due to the fact that the removal torque acts on each tooth individually,the torque can be converted into a shear force that acts on across-sectional area of where each tooth contacts its adjoining surface,i.e. the shear force area. For the teeth on the locking ring 26, theshear force area is the area where each tooth 36 contacts the face 48.For the teeth on the nut 24, the shear force area is the area where eachtooth 36 contacts the recessed face 38.

Torque is defined by the following equation: T=F×D, where:

-   -   T=Torque    -   F=Force    -   D=Distance between the revolving axis of the nut or ring and the        force acting on the tooth

Because the force acting on each tooth is spread across its length,which is measured along the radius of the nut 24 or the interlockingring 26, it can be assumed that the force acts at the center of eachtooth. This causes the distance of the torque reaction to occur betweenthe revolving axis of the nut or ring and the center of each tooth.

To determine the removal torque of a given tooth pattern, the followingvariables must be known:

-   -   G=Shear modulus of elasticity of the given material    -   L=Length (measured along the radius) of a given tooth where it        contacts its adjoining surface    -   W=Width (measured along the circumference) of a given tooth        where it contacts its adjoining surface    -   D=Distance from the revolving axis of the nut or ring to the        center of the tooth    -   N_(t)=Total number of teeth on the nut or ring (whichever has        less teeth)

First the maximum shear force, F_(max), is determined by the followingequation:

F _(max) =N _(t) [G(LW)]

The maximum removal torque, T_(max), can then be calculated with:

T _(max) =F _(max) ×D

The number of teeth 36 formed on the nut 24 and the number of teeth 46formed on the interlocking ring 26, which is controlled by the pitch,i.e. the distance between the leading edges of adjacent teeth (or thedistance between the trailing edges of adjacent teeth) which is measuredin degrees or radians, controls the amount of movement in theuntightening rotational direction before the teeth engage one another.The greater the number of teeth either on the interlocking ring 26 orthe nut 24, i.e. the smaller the pitch, the lesser the amount ofrotation is allowed in the untightening rotational direction.Furthermore, the greater the number of teeth that engage one another,the more surface area is provided to counteract rotational movement inan untightening rotational direction. Accordingly, less shear force isexerted on each tooth. In the depicted embodiments, approximately fortyteeth 36 are formed in the nut 24 and approximately fifty teeth 46 areformed on the interlocking ring 26, and the number of teeth may likelybe a function of the diameter of the bolt 10 that is to be received bythe locking nut assembly 12.

In the depicted embodiment, the pitch measures six degrees; however, thepitch can be up to about 10 degrees. For the depicted embodiment, sixdegrees of rotational movement in the untightenting direction is allowedbefore the teeth fully engage one another. A small pitch results in thebolt 12 still carrying its tensile load after one has attempted toremove the nut 24 from the bolt 12. The pitch can be lessened,especially for larger diameter fastener assemblies to allow for evenless rotational movement in the untightening direction.

The components of the fastener assembly can be made from a number ofdifferent manufacturing processes. Two of these processes will bedescribed in more detail. The nut 24 and the interlocking ring 26 can bemade using a powdered metal process or a metal injection moldingprocess. By making the nut and the interlocking ring using either ofthese processes, the negative rake angle for the teeth can be achievedwith significantly less manufacturing costs than other known processes.For example, machining a negative rake angle would require a specialcutter that is shaped like the gap between adjacent teeth (either tooth36 or 46). Each tooth would have to be individually machined and wouldrequire the use of a special indexer and a special cutter.

For both the powdered metal process and the metal injection moldingprocess, a powdered metal is placed into a mold, either a nut mold or aninterlocking ring mold. More specifically for the metal injectionmolding process, a binder is typically added to the powdered metal thatis placed in the mold so that the metal flows similar to a plasticinjection molding process. The powdered metal and/or powdered metal andbinder mixture is then compressed while restricted in the mold to form agreen nut or interlocking ring. The powdered metal is then sinteredbelow the melting point of the particular metal or alloy. The sinterednut or interlocking ring is then sized to form the corresponding teeth.In such an operation, the root of each tooth is supported while a forceis applied at or near the apex of each tooth to form the negative rakeangle. After the sizing operation, the sintered nut or interlocking ringis again heat treated for improved strength and hardness.

With reference to FIG. 7, in another embodiment, an insert ring 84 isprovided instead of the toothed face of the nut. The insert ring 84 canbe made from the powdered metal process or the metal injection moldingprocess described above. The insert ring 84 includes a plurality ofteeth 86 formed on a first face 88 of the insert ring. The insert ring84 in the embodiment depicted in FIG. 7 has a circular peripheral edge90 that is eccentric with the opening 42 of the interlocking ring 26.The eccentric insert ring 84 is dimensioned to be received inside aneccentric counterbore 92 that leads to a threaded receptacle 94 that isconcentric with the opening 42. The threaded receptacle 94 is similar tothe threaded bore 32 described with reference to FIGS. 3 and 4. Theeccentric counterbore 92 is similar to the counterbore 34 of the nut 24,with the exception that its periphery is eccentric with the threadedreceptacle 102.

The locking ring 26, which has been described above, can be used withthe insert ring 84. Also, a biasing member 96 similar to the biasingmember 28 described with reference to FIGS. 3 and 4, can also be used.The biasing member 96 includes an opening 98 that is dimensioned toreceive a bolt, such as the bolt 10 and is concentric with the openings42 and 94. The biasing member also has an eccentric circular peripheraledge 100 that is dimensioned to be received inside the eccentriccounterbore 92.

The eccentric peripheral edge 90 of the insert ring 84 and the eccentricconfiguration of the counterbore 92 inhibits or prohibits rotation ofthe insert ring 84 inside the counterbore 92 as the bolt is tightenedinto the threaded receptacle 94. The teeth 46 of the interlocking ring26 and the teeth 86 of the insert ring 84 cooperate with one anothersimilar to the nut locking assembly described with reference to FIGS. 3and 4. The eccentric peripheral edge 100 of the biasing member 96 alsoprohibits or substantially inhibits the biasing member from rotatinginside the counterbore 92. In an alternative embodiment, the eccentricperipheral edges 90 and 100 and the counterbore 92 can be madenoncircular so that the biasing member 96 and the insert ring 90 do notrotate in the counterbore as the bolt 12 is tightened into the threadedreceptacle 94.

As seen in FIG. 7, an alignment hole 102 is formed in the counterbore92. With reference to FIG. 8, a small protuberance 104 extends from asecond face 106 of the insert ring 84, the second face being oppositethe first face 88 having the teeth 86. The small protuberance 104 fitsinto the opening 102 to align the insert ring. The insert ring 84 alsoincludes two through bores 108, one on each side of the protuberance104. The biasing member 96 includes two small posts 110 that arereceived inside the through bores. Accordingly, the interlocking ring 26can be received inside a circular recess 111 (only partially shown) andsandwiched between the biasing member 96 and the insert ring 84 and allthree pieces can be inserted together into the counterbore 92.

FIGS. 9-11 disclose a tool that can be used to remove the nut lockingassembly 12 from the bolt 10 without having to shear the teeth 36 and 46in the nut locking assembly. The removal tool 112 includes a pinretainer 114, a pin holder 116, a retainer ring 118, and a plurality ofpins 122. The removal tool 112 cooperates with the nut locking assembly12, as seen in FIG. 10, in a manner which will be described in moredetail below.

With reference to FIG. 11, the pin retainer 114 includes a threaded boss124 that is adapted to threadingly engage the bolt 10 (FIG. 1). The pinretainer 114 includes a circular channel 126 defined between thethreaded boss 124 and an outer peripheral wall 128 of the pin retainer.The circular channel is dimensioned to receive the pin holder 116, whichalso has a circular ring-like configuration. The pin retainer 114 alsoincludes an annular shoulder 130 that is axially spaced from a base wall132 of the pin retainer 114. In the depicted embodiment, the annularshoulder 130 is spaced from the base wall 132 a dimension that is equalto the thickness of the pin holder 116. The retainer ring 118 isreceived on the annular shoulder 130 to retain the pin holder 116 insidethe circular chamber 126.

The pin holder 116 includes a central opening 134 that is dimensioned toreceive the threaded boss 124 so that the pin holder 116 is seatedinside the circular channel 126. The pin holder 116 includes a pluralityof axially aligned pin openings 136 that are dimensioned to receive thepins 122. Each pin 122 includes an appropriately shaped shank 138 forreceipt by the pin openings 136 and a head 142 at one end of the shank.The pin openings 136 and the pin holder 116 can include a counterbore(not visible) so that the head 142 is countersunk into the pin holder116.

The retainer ring 118 includes a central opening 144 that is dimensionedto fit around the pins 138, as more clearly seen in FIG. 8. The retainerring 118 can attach to the annular shoulder 130 and/or side wall 128 ofthe pin retainer 114. Alternatively, the retainer ring 118 can simplysnugly fit inside the side wall 128 and be made of a resilient materialthat biases outward to retain the pin holder 116 in the circular channel126.

With reference back to FIG. 10, the removal tool 112 is threaded onto aportion of the bolt (not shown in FIG. 10) that extends from the nut 24.The pin holder 116 is positioned inside the circular channel 126 so thatthe pins 122 freely rotate about a longitudinal axis of the bolt 10 (notshown in FIG. 10) as the removal tool is threaded onto the bolt. Thepins 122 are then aligned with axial openings 144 formed in the nut 24,which are also visible in FIGS. 3 and 4. The removal tool 12 is thenthreaded onto the bolt so that the pins 122 advance through the axialopenings 144 in the nut 24 until they extend from the recessed face 38of the nut 24. The pins 122 will engage the interlocking ring 26 (notshown in FIG. 10) and overcome the biasing force of the biasing member28 axially moving the interlocking ring away from the recessed face 38.Accordingly, the teeth 46 of the interlocking ring 26 disengage theteeth 36 of the nut 24. This allows the nut 24 to be unscrewed from thebolt 10 without any loss of material in the nut 24 of the interlockingring 26.

With reference to FIGS. 12-14, an alternative embodiment of a removaltool 150 is shown. In this embodiment, the removal tool includes asocket 152 that includes a central opening 154 having a hexagonallyshaped configuration that is adapted to receive the nut 24. The shape ofthe central opening 154 can be other configurations to conform to nutshaving other configurations. The central opening 154 will also includenotches cut out of the hexagonally shaped opening to accommodateinternal components of the removal tool that will be described below.The socket 152 is adapted to work with a conventional socket wrench andcan include an opening 156 (FIG. 14) at one end for receiving the socketwrench. A locking ring 158 is disposed at an end of the socket 152 wherethe hexagonal opening 154 terminates. The locking ring 158 includes tabs160 that are adapted to engage L-shaped notches 162 formed on the sideof the annular shoulder 56 of the nut 24. Notches 166 are formed in thesocket 152 to limit the rotational movement of the locking ring 158. Aretainer ring 164 retains the locking ring 158 to the socket 152.

Internal components of the removal tool 150 are housed in the socket152. With reference to FIG. 13, the removal tool 150 includes aplurality of pins 168 that are received inside the axial bores 144 ofthe nut 24, similar to the pins 122 described with reference to theremoval tool 112. A movable pin support 172 includes a plurality ofopenings 174 that receive the pins 168. The movable pin support has ahexagonally shaped peripheral edge 176 and a pair of diametricallyopposed ears 178 extending from the peripheral edge 176. The ears 178include threaded openings 182.

A pin base holder 184 supports the base of each pin 168. The pin baseholder 184 includes a plurality of openings 186 dimensioned to receivethe pins 168. The base pin holder 184 also includes a hexagonalperipheral edge 188 having two notches 192 that are diametricallyopposed from one another and aligned with the ears 178 of the movablepin support 172. The base pin holder 184 serves a similar function asthe pin holder 116 disclosed in FIGS. 9-11.

A pin base retainer 194 abuts the pin base holder 184 to retain the pins168 in a similar manner to the pin retainer 114 disclosed with referenceto FIGS. 9-11. The pin base retainer includes a hexagonal peripheraledge 196 and two notches 198 aligned with the notches 192 in the pinbase holder 184. The movable pin support 172, the pin base holder 184,and the pin base retainer 194 each have a similar configuration to thepolygonal configuration of the nut 24 to which the removal tool 150 willremove.

Outer threaded rods 202 are received by the threaded openings 182 in themovable pin support 172. The outer threaded rods 202 include and/orattach to heads 204 that contact a first shoulder 206 (FIG. 14) of thesocket 152. Biasing members, which in this embodiment are helicalsprings 208, receive the outer threaded rods 202 and are disposedbetween the movable pin support 174 and a second radial shoulder 210(FIG. 14), which is spaced from the first radial shoulder 206 towardsthe movable pin support.

A central shoulder screw 212 connects the pin base holder 184 and thepin base retainer 194. A biasing member 214, which has a greater biasingforce than the helical springs 208 and the biasing member 28 for thelocking nut assembly 14, biases the pin base holder 184 and the pin baseretainer 194 from a central socket shoulder 216 (FIG. 14), which has athreaded opening 218 for receiving the screw 212.

To remove the nut 24, the removal tool 150 is aligned so that the pins168 can be received in the axial bores 144 of the nut 24. The socket 152is then pushed towards the shoulder 56 of the nut 24 and is rotated sothat the tabs 160 engage in the L-shaped notches 162 of the nut 24. Whenthe locking ring 156 is engaged with the shoulder 56 of the nut 24, themovable pin support 172 is moved towards the pin base holder 184 and thepins 168 extend from the recessed base 38 of the nut 24 to overcome thebiasing member in a similar manner to the removal tool described withreference to FIGS. 9-11. The pins move axially in bores 222 (FIG. 14)formed in the socket 152. The socket 152 can then be used to remove thenut 24.

With reference to FIG. 15, a cover 230 can be provided to prevent anydebris from traveling through the exposed ends of the longitudinal bores144 (FIG. 12) that receive the pins 168. The cover 230 fits on to theend of the nut 24 opposite the shoulder 56. Small protuberances 232 thatare dimensioned to fit inside the ends of the bores 144 extend from aface of the cover 230. The cover 230 includes a central opening 234 thatreceives the bolt 12. To remove the nut 24 from the bolt 12, the cover230 would be removed from the nut and then the removal tool 112 or 150could be used to remove the nut.

A self-locking fastener assembly has been described with reference tospecific embodiments. Modifications and alterations will occur to thoseupon reading and understanding the preceding detailed description. Theinvention is not limited to only those embodiments described above.Instead, the invention is intended to cover all modifications andalterations that come within the scope of the appended claims and theequivalents thereof.

1. A fastener assembly comprising: a threaded bolt including at leastone longitudinal groove; and a locking nut assembly comprising: a nutadapted to threadingly engage the bolt, the nut including a threadedbore dimensioned to receive the bolt, a counterbore axially aligned withthe threaded bore and a plurality of teeth formed on a recessed facethat is normal to a longitudinal axis of the nut, each tooth for the nutbeing disposed at a negative rake angle; a locking ring adapted toengage the bolt and the nut and dimensioned to be at least partiallyreceived in the counterbore, the locking ring including at least oneinwardly protruding tab dimensioned to be received by the at least onelongitudinal groove and a plurality of teeth formed on a face that isnormal to a longitudinal axis of the ring, each tooth for the lockingring being disposed at a negative rake angle and dimensioned tocooperate with a corresponding tooth for the nut; and a biasing memberadapted to bias the locking ring and dimensioned to be at leastpartially received in the counterbore.
 2. The assembly of claim 1,wherein the biasing member comprises a ring made from an elastomericmaterial.
 3. The assembly of claim 1, wherein the biasing member isadapted to retain the locking ring in the counterbore.
 4. The assemblyof claim 3, wherein the biasing member includes outwardly protrudingfingers and the nut includes recesses dimensioned to receive thefingers.
 5. The assembly of claim 1, wherein the counterbore has a depthabout equal to or slightly less than a maximum thickness of the lockingring and a maximum thickness of the biasing member.
 6. The assembly ofclaim 1, wherein the nut includes at least two longitudinal boresradially spaced from the threaded bore extending from an end face of thenut that is spaced from the recessed face, each of the at least twolongitudinal bores extending from the end face to the recessed face. 7.The assembly of claim 6, further comprising a removal tool comprising apin retainer having a threaded bore adapted to be threaded onto the boltand at least two pins extending from the pin retainer that are adaptedto be received by the at least two longitudinal bores of the nut.
 8. Theassembly of claim 6, wherein the nut includes a notch formed in an outerside wall, the notch being adapted to receive at least a portion of aremoval tool.
 9. The assembly of claim 8, further comprising a removaltool, the removal tool comprising: a socket having an opening adapted tocooperate with the nut and an inwardly extending tab for engaging thenotch; and at least two longitudinal pins disposed in the socket andadapted to be received by the at least two longitudinal bores of thenut.
 10. The assembly of claim 1, wherein each tooth for the nut and forthe locking ring is disposed at a negative rake angle between about 1degree and about 10 degrees.
 11. The assembly of claim 1, wherein boththe ring and the nut are made from powdered metal.